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Title Tuning the coupling of an individual magnetic impurity to a superconductor: quantum phase transition and transport
Authors Laetitia Farinacci, Gelavizh Ahmadi, Gael Reecht, Michael Ruby, Nils Bogdanoff, Olof Peters, Benjamin W. Heinrich, Felix von Oppen, Katharina J. Franke
Journal Physical Review Letters
Vol. 121, 2018, pg. 196803


Abstract The exchange scattering at magnetic adsorbates on superconductors gives rise to Yu-Shiba-Rusinov (YSR) bound states. Depending on the strength of the exchange coupling, the magnetic moment perturbs the Cooper pair condensate only weakly, resulting in a free-spin ground state, or binds a quasiparticle in its vicinity, leading to a (partially) screened spin state. Here, we use the flexibility of Fe-porphin molecules adsorbed on a Pb(111) surface to reversibly and continuously tune between these distinct ground states. We find that the FeP moment is screened in the pristine adsorption state. Approaching the tip of a scanning tunneling microscope, we exert a sufficiently strong attractive force to tune the molecule through the quantum phase transition into the free-spin state. We ascertain and characterize the transition by investigating the transport processes as function of tip-molecule distance, exciting the YSR states by single-electron tunneling as well as (multiple) Andreev reflections.



BibTeX entry
    @article{ AGP-2018:108,
      title = { Tuning the coupling of an individual magnetic impurity to a superconductor: quantum phase transition and transport },
      author = { Laetitia Farinacci, Gelavizh Ahmadi, Gael Reecht, Michael Ruby, Nils Bogdanoff, Olof Peters, Benjamin W. Heinrich, Felix von Oppen, Katharina J. Franke },
      journal = { Physical Review Letters },
      volume = { 121 },
      year = { 2018 },
      pages = { 196803-- },
    }